Hi,  you need to use graphite electrode to avoid the pits.
we use both (steel and graphite electrodes) in U of Michigan, and the
results are consistent.

jun
----- Original Message -----
From: "Brett Swope" 
To: 
Sent: Wednesday, July 31, 2002 9:47 AM
Subject: [mems-talk] Anodic Bonding - Glass Pits


> I am attempting to set up an anodic bonding tool that will be able to
> uniformly bond 3" wafers.  At this point I am able to bond Corning 7070
> Borosilicate glass to Si wafers but after the wafers have cooled there
appears
> to be minor defects in the glass surface in the form of 'pits'.  Each pit
is
> less than 50 um in diameter and hundreds are spread randomly throughout
the
> glass.  My setup is as follows:
>
> Temp: 400 C
> Voltage: 500-1200 V
> Time: 1-5 mins
> Electrodes: 304 Stainless Steel (lapped and polished on glass contact
> surface)
>
> Has anyone ever heard of this?  I have looked through some literature but
> haven't found anything like this.
>
> Any help is appreciated!
> Brett Swope
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